Measurement of filtering rates of the salp, Thalia democratica, from the Great Barrier Reef lagoon

Measurements of the feeding rates of a salp, Thalia democratica, were made using an experimental perspex chamber deployed during 12 dives off Cape Cleveland, in the Great Barrier Reef lagoon. Zooplankters were captured in the chamber, 50 ml of labelled suspended particles were injected into it, mixed, and then 20 ml drawn out for sampling. After 30 mins, a second 20 ml sample was made.Upon return to the laboratory, both samples were sorted, measured (length) using a dissecting microscope, and identified.Salps were placed in scintillation vial either singly or in small groups of the same size. The d.p.m of 14C and 3H was determined and the filtering rate calculated (ml/salp-hr). To test a method for measuring rates of feeding by the salp, Thalia democratica, on phytoplankton and bacteria. Phytoplankton cultured for experiment were: Isochrysis galbana, Pavlova (Monochrysis) lutheri and Thalassiosira pseudonana. Bacteria were: Vibrio alginolyticus, and on one occasion Serratia marcescens.